Question: Can one fulfill his obligation to hear a blessing, Torah reading, or Megillah reading by hearing these things on the radio? Similarly, may one answer Amen to a blessing one hears recited on the radio?
Answer: We must first introduce this topic by discussing the law that “one who hears is tantamount to reciting” as follows:
Our Sages taught us (Sukkah 38b) regarding all Torah laws that apply to speech or recitation, such as Birkat Hamazon and the like, that one who hears the blessing recited is tantamount to having recited the blessing himself. For instance, if one wishes to recite the “Boreh Peri Ha’etz” on a fruit before eating it and his friend wishes to do the same, both individuals can fulfill their obligation to recite a blessing with a blessing recited by only one of them by one individual reciting the blessing and having in mind for the other individual to fulfill his obligation by listening. This is indeed our practice regarding Kiddush and the “Hamotzi” blessing on Shabbat whereby the head of the household recites the appropriate blessings on the wine and the bread and the rest of the family members answer Amen, taste a bit of the wine and bread, and do not proceed to recite their own respective blessings since they have already fulfilled their obligation to do so by listening to the blessings recited by the head of the household.
Another fairly simple law that we must address is that one is obligated to answer Amen upon hearing any blessing recited by a fellow Jew, even if one does not intend to fulfill his obligation by listening to this blessing.
Let us now discuss the law regarding answering Amen to a blessing one hears on the radio or over the telephone. We find a similar situation in the Gemara (Sukkah 51b) regarding the Jews of the large metropolis of Alexandria in Egypt who fled there Israel following the destruction of the Bet Hamikdash and remained there until Alexander the Great destroyed this city. In this city, the synagogue the Jews prayed in was tremendous in size and there were a multitude of people praying there, so much so that there was a large wooden podium in the middle of the synagogue but congregants could not hear the blessings recited by the Chazzan and answer Amen to them due to the sheer size and occupancy of the synagogue. In order to solve this issue, the care-taker of the synagogue would hold kerchiefs in his hand and when it was time for the congregation to answer Amen, he would wave the kerchief in his hand as a signal, at which point the congregation saw this and answered Amen.
The Tosafot (ibid. 52a) explain that although the congregation would answer Amen to the blessings recited by the Chazzan, they would, nevertheless, not be able to fulfill their obligation using the law of “one who hears is tantamount to having recited,” for they would not hear the words uttered by the Chazzan. Only with regards to answering Amen to a blessing do we say that one need not actually hear the blessing and it is sufficient to merely know that someone is reciting a blessing now and which blessing is being recited in which case one may, in fact, answer Amen.
Thus, the same applies to a radio or telephone in that although the sound one hears on the radio or over the telephone is not the actual voice of the individual reciting the blessing and is merely an electronically generated noise produced by the individual, this is nevertheless similar to the scenario in the Great Synagogue of Alexandria and one must answer Amen to a blessing one hears being recited on the radio or over the telephone. On the other hand, regarding the law of “one who hears is tantamount to having recited” and fulfilling one’s various obligations with readings heard on the radio and over the phone, such as hearing Megillah reading on the radio, one has certainly not fulfilled his obligation in this manner, for one has not heard a reading of a human voice; this is similar to one having heard a recording of Megillah reading in which case one has certainly not fulfilled his obligation (Responsa Yechave Da’at, Volume 3, Chapter 54).
In the following Halacha, we shall, G-d-willing, delve into this topic further.